I have an 'o5 F4i, Yosh TRS race slipon, PCIII, and had Charles at HDF1Motorsports custom map it. His Factory Pro Eddy Current dyno read 87HP, which if I do the math would be 97-100hp on a regular Dynojet Dyno. I think the conversion is to take the Factory Pro Eddy Current results and multiply by 1.15, according to Sportbike Magazine.

In any case, I went down 1 tooth up front and up 1 in the back, so 16/46 to 15/47. Added a bit of punch at the expense of top end. The other thing is that my speedo is now quite a bit off. On the Dyno, the speedo read 161mph, but the Dyno itself measured the top speed of the bike at 138mph. So at top speed, the speedo is off by more than 20mph. Ouch.

What I am wondering, is does lowering that gearing really add more acceleration, or is it more of a question of having to do less foot-work to make sure that you are in the meat of your power band?

Would my bike do a faster 1/4 now than it would with stock gearing, all other things being equal? Am I really getting better acceleration, or is it just that I do not have to have the revs up as high to make power?

I am just weighing my options here and making sure that I have the bike performing as best as possible. I am concernind that if the top speed on the Dyno was only 138mph, that with my 220 pounds and wind resistance, it might be considerably less than that.

What do you guys think? Keep the current gearing, or go back to stock with perhaps a 520 conversion kit to lighten up the drivetrain?

As far as the engine goes, I think it is tuned just fine, so now I am trying to get the most out of gearing, and then comes suspension, making sure that I get the proper springs for my weight and setting it up right.

Looking at reviews, the bike does a 1/4 mile in 10.74 at 127mph or something. Will the lowered gearing theoretically increase or decrease that time? If my top speed is now barely that fast, I am wondering if this gearing might be hurting me.

 

squire
I did the -1 front rear stock. Without measuring(have not clocked with stock gearing) I honestly feel that the acceleraton is better. As far as 1/4 times have not seen or heard of the "stock" 10 sec other than the back page of MC mag. run. But then again I haven't really looked all that hard either. The only f4i I have ridden is my own and it just does not have as much power as the r6 for the 1/4. don't get me wrong I love the bike and have owned an r6 also. for ease of ride and comfort f4i hands down. But if I wanted a bike for the 1/4 I would have to go with the other bike. I am only 5'10" at 180 and getting older by the moment so I perfer the bike with ther more comfort, the f4i fits me well. No road racing for me other than the cleaning out of carbon from time to time and the top speed test here and there and maybe a few back road twisties doh... I went to the 1/4 this past weekend but they were running pro gas and I was not about to pay 60 bucks to race brackets. personal best 12.20 at 111mph. will keep you posted.

 

dood you should have gone with a 600rr if you wanted it to be faster and down the front more

 

I considered it, but at 6'4 the rr was not nearly as comfortable as the F4i. I will keep this bike for a year or so and then trade up to something bigger.

 

I think a -1 gearing definately makes it faster down the 1/4.

I have an F4 and have taken it to the drag strip three times and on first two occasions my best times were 12 flat (this is with stock gearing). Both these times I was racing another F4 and we were evenly matched for times. I did the -1 conversion and the next time I went down my best time was 11.9. The F4 I raced did a best for the night of 12.2 and like I said before we were getting the same times when I had stock gearing.

So you can either say it made a .1 or a .3 difference to my bike but it was definately faster down the 1/4 mile with the -1.

And dont worry about the times they get in magazines theres no way a someone who isn't a prefessional rider is going to do 10.7s on a stock F4i

 

Hmmm... Well, I liked they way it was riding today.

1/4 mile times are not THAT important to me, but my concern was that my bike might be almost ready to top out at 1/4 mile. I mean, if it was able to do one in the 125-130mph range, and the bike is only able to do 138 or so top speed...

Of course the best thing to do would be to get an R1 and have top speed and massive acceleration. :-)

 

Why stop there...go with the Turbo Hayabusa then...if all you want if down the straight go for THE bike...but there is a reason why HONDA owns the 600 class.....
Things that make you go hmmm